1. Field of the Invention
The present invention relates generally to a wheel end assembly and, more particularly, to a wheel end assembly utilizing an electric motor in conjunction with inboard and outboard reduction gear sets to drive an individual wheel of a motor vehicle.
2. Related Art
A variety of wheel end assemblies are known in the art which utilize electric motors and double reduction gear sets, of the planetary type, to drive individual wheels of motor vehicles. However, based on the particular configuration of assembly components and/or the spacial relationship among individual components which defines the assembly envelope, prior wheel end assemblies are typically subject to one or more of the following disadvantages. Prior double reduction wheel end assemblies typically utilize a primary, or high-speed, reduction gear set of a conventional planetary type wherein a rotatable planet gear carrier provides the planetary output and a plurality of planet gears rotate with the carrier. In relatively high speed applications such assemblies have the disadvantages of requiring precise balancing of the planet carrier and creating relatively high centrifugal forces acting on the planet gears which may result in reduced gear bearing life and increased gear mesh noise relative to a planetary-type gear set utilizing a stationary planet carrier. The primary and secondary speed reduction gear sets of prior art double reduction wheel end assemblies are often positioned axially adjacent one another which, for a given vehicle wheel base and optimum wheel hub bearing location, can result in the assembly extending farther inboard than necessary which in turn may compromise design requirements of the associated vehicle. For instance, if such a wheel end assembly is utilized to drive a commercial bus wheel, the available space for the bus passenger aisle may be reduced. Additionally, other known wheel end assemblies are configured such that the load path for reacting the vehicle weight passes through at least one of the reduction gear sets resulting in undesirable gear mesh deflections. Further, the spacial relationship between other assembly elements, such as the brake means and the primary and secondary speed gear sets, may be such that an optimum packaging envelope of the assembly is not achieved.
In view of the foregoing disadvantages associated with prior wheel end assemblies, applicants' invention is herein presented.